THE MOST IMPORTANT INSECT PESTS in FOREST ECOSYSTEMS of VOJVODINA and THEIR SUPPRESSION DURING the PERIOD 2004-2013 Predrag

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Silva Balcanica, 15(2)/2014

THE MOST IMPORTANT INSECT PESTS IN FOREST ECOSYSTEMS OF VOJVODINA AND THEIR SUPPRESSION DURING THE PERIOD 2004-2013

Predrag Pap, Milan Drekić, Leopold Poljaković-Pajnik, Miroslav Marković, Verica Vasić Institute of Lowland Forestry and Environment University of Novi Sad

Abstract

The paper presents a chronological survey of the most important insect pests identified in Vojvodina forests during the period 2004 - 2013, and the activities on their monitoring and suppression. To protect the forests against insect pests, their characteristics have to be known, they should be detected in time, and finally suppressed by the most efficient methods and means. During the past period, the health state of forest ecosystems was satisfactory, which is the best proof of the good team work of the professionals and scientists in this field, so it can be a good example to forest profession in general. Key words: Vojvodina, forest ecosystems, insect pests, protection, control

INTRODUCTION

Vojvodina is a region in the southern part of the Pannonian Plain with the lowest percentage of forests in Europe. Forests and forest plantations occupy 137,000 ha, so forest cover accounts for only 6.4% of the area. The largest forest complexes are located on Fruška Gora, Vršačke Planine, Deliblatska Peščara and Subotička Peščara and along the large rivers – Danube, Tisza, Sava, Bosut, and Tamiš. With the exception of the above complexes, there are almost no forests, or they occur in fragments. The low percentage of forests and their uneven distri- bution in this specific primarily agricultural area makes the forests in Vojvodina especially endangered ecosystems. In addition to specific climate, edaphic, and hydrological conditions which are mainly decisive in the selection of the tech- nology and the species for the establishment of forests and plantations, it is very important to investigate the significance of pests and their impact on the vitality and survival of forest ecosystems. Among numerous pests identified in forests, plantations and nurseries, insect pests hold a special place and significance. During the period 2004-2013, intensive monitoring of insect pests consisted of numerous health inspections of Vojvodina forests, plantations and nurseries. Thanks to a

68 well-organised service for forecasting and reporting activities managed by Insti- tute of Lowland Forestry and Environment, the situation was regularly updated, the population levels of insect pests were analysed, as well as the need for suppression measures using the most favourable methods. Based on the reports of the forecasting and reporting service, official documents, records, and our authentic notes and observations, this paper provides a chronological overview of the most important insect pests in Vojvodina forests during the period 2004-2013. The data collected on insect pests in this area are not only of local significance, but also of wider significance for forestry profession. The aim of this paper was to inform forestry professionals on the most important insect pests in forest ecosystems in Vojvodina, as well as on the measures that were taken for their suppression within the study period.

INSECT PESTS IN FORESTS, PLANTATIONS AND NURSERIES AND THEIR CONTROL

Lymantria dispar L. – gipsy moth It is evaluated as the major threat of broadleaf forests in Vojvodina. From the historical aspect, this pest has always been present in the forests of oaks and other tree species, often occurring in enormous proportions, i.e. in densities fatal for forest sustainable management and maintenance if control measures are not undertaken. During the past decade, gipsy moth outbreaks occurred during the periods 2004- 2006 and 2010-2013; it was successfully suppressed both from the air and from the ground on large areas (Table 1). The seventeenth gipsy moth outbreak in Vojvodina started in 2003. Aerial suppression was organised and carried out during 2004-2006 in the most infested forests (Drekić et al. 2006). In 2004, in the area of Forest Estate Sremska Mitrovica, oak stands were treated in Posavina (loc. Senajske Bare II – Karakuša) on 1521.0 ha, preparation Decis 2.5-EC (Table 1). The largest forest complexes in Vojvodina were treated in 2005. In the area of Forest Estate Sombor, oak stands were treated at Monoštorske Šume (3580.5 ha) and Karapandža (1698.7 ha), and a smaller part in the forests managed by the Public Water Management Company ‘Vode Vojvodine’ (328.5 ha). In Forest Estate Sremska Mitrovica, small complexes of oak stands were treated from the air at the sites Radinska-Vranjak (99.7 ha) and Rađenovci-Novi (314.4 ha). In the above actions, the biotechnical preparation Dimilin SC-480 and insecticide Decis 2.5-EC were applied over the area of 6,021.8 ha (Table 1). In the spring 2006, gipsy moth was suppressed from the air in oak stands in Posavina (loc. Rađenovci-Novi) using the preparation Decis 2.5-EC (244.5 ha), and experimentally using the bio-pesticide based on Bacillus thuringiensis (143.4 ha). All the above aerial actions were assessed as very successful in all stages, both from the organisa- tional aspects and from the aspect of undertaken activities. The result of gipsy moth suppression from the air and from the ground was its multiple reduction in the in-

69 Table 1 Areas infested by gipsy moth in Vojvodina prior to caterpillar hatching and areas treated from the air and from the ground during the period 2004-2013

Total Gipsy moth infested Gipsy moth suppression from the air (ha) and the applied suppression Year area preparations from the (ha) ground (ha)

Decis 2.5-EC (active substance deltamethrin) 2004 18 316.0 1521.0 (0.2 L/ha + 2.8 L naphtha D 1/ha) 16 795.0 (FE Sremska Mitrovica, 1521.0 ha)

Decis 2.5-EC (a.s. deltamethrin) (0.2 L/ha + 2.8 L naphtha D1/ha) (FE Sombor, 2624.2 ha; FE Sremska Mitrovica, 414.1 ha) 2005 18 145.0 6,021.9 Dimilin SC-480 12 123.1 (a.s. diflubenzuron) (180 mL/ha + 0.8 L white oil/ha + 3.2 L water/ha) (FE Sombor, 2655.1 ha; PWMC ‘Vode Vojvodine’, 328.5 ha) Decis 2.5-EC (a.s. deltamethrin) (0.2 L/ha + 2.8 L naphtha D1/ha; 244.5 ha) 2006 2222.7 387.9 1834.8 Bacillus thuringiensis (experimental, 143.4 ha) (FE Sremska Mitrovica, 387.9 ha) 2007 794.1 - - 794.1 2008 442.5 - - 442.5 Etiol-ULV (a.s. malathion) (1l/ha + 2l naphtha/ha; 88,7 ha) 2009 506.2 132.8 Avaunt 15-SC 373.4 (a.s. indoxacarb) (experimental, 44.1 ha) (FE ‘Banat’ – Pančevo, 132.8 ha) 2010 2179.5 - - 2026.5 Foray 48B (3l/ha) 2011 6013.3 4,066.0 (Bt subsp. kurstaki) 1947.3 (FE Sremska Mitrovica, 4,066.0 ha) Laser 240SC (a.s. spinosad) 2012 6100.1 1,893.4 4206.7 (0.1 L/ha + 1.5 L white oil/ha + 1.4 L water/ha) (FE Sremska Mitrovica, 1893.4 ha) 2013 3,131.5 - - 423.3 fested area, so in the summer and autumn 2006, gipsy moth egg masses were found on 794.1 ha, i.e. on about 23 times smaller area compared to the outbreak culmina- tion in 2004 and 2005 (Table 1). In poplar plantations at Gornje Potamišje (Forest Estate ‘Banat’ – Pančevo),

70 the gipsy moth was permanently present during the past period. The infestations were repeated each year, because a part of egg masses deposited on higher posi- tions on the trees could not be treated nor soaked with naphtha. In the spring 2009, it was decided to perform aerial spraying of the plantations with the preparation Etiol ULV on 88.7 ha. The preparation Avaunt 15SC was applied experimentally on 44.1 ha (Table 1). Unfortunately, Avaunt 15SC had no effect on gipsy moth caterpillars, so the trees were defoliated. As it could be expected, gipsy moth repeated the attack in the following year. Owing to the presence of flood water during the winter and spring 2010, the egg masses were not soaked, so caterpillars consumed 70% of the foliage – predominantly in the plantations nearing the end of the rota- tion. In this area, gipsy moth has been in the decline phase from 2011. In our opin- ion, the multiannual, chronic gipsy moth infestations in poplar plantations in the area of Gornje Potamišje are the consequence of a less favourable site (humogley) for poplar cultivation. Gipsy moth reappeared over large areas in Vojvodina in 2010 (2179.5 ha). In the infested forests and plantations, the egg masses were soaked with naphtha, but with partial success, as the outbreak was not stopped. In the spring 2011, just before caterpillar hatching, gipsy moth egg masses were detected in Vojvodina on 6013.3 ha of forests and plantations – predominantly in the area of Forest Estate Sremska Mitrovica. The most frequently infested forests of this Estate were treated from the air in the spring 2011 using the preparation Foray 48B on the area of 4066.0 ha (loc. Đepuš, Radinska-Vranjak, Senajske Bare II-Karakuša, Grabovačko-Vitojevačko Os-

Fig. 1. Gipsy moth caterpillar killed by Fig. 2. Gipsy moth caterpillars killed by nuclear polyhedrosis virus (FE Sremska Entomophaga maimaiga (FE Sremska Mitrovica, loc. Galovača, June l0th, 2013) Mitrovica, loc. Naklo, June l3th, 2013)

71 trvo and Matijevica-Kadionica). An additional aerial spraying was undertaken in the spring 2012. Oak stands at Rađenovci-Novi, Kućine-Naklo-Klještevica and Senajske Bare II-Karakuša were treated with the insecticide Laser 240SC on 1893.4 ha (Table 1). The actions were evaluated as very successful in all segments, so in the summer and autumn 2012, gipsy moth egg masses were found on significantly smaller areas and in far lower numbers. The exception were oak stands at Galovača, Naklo and Radinska, where gipsy moth deposited a great number of egg masses (more than 500 egg masses/ha). Despite the well-timed procedure for the purchase of preparation for gipsy moth suppression from the air in the spring 2013, the treatment was aban- doned because of an unsuccessful tender. For this reason, oak stands at the location Galovača (281.0 ha) were defoliated, and at Naklo defoliation accounted for 50% on cca 85-90 ha. During the spring inspection of these stands, it was found that masses of gipsy moth caterpillars were killed by nuclear polyhedrosis virus disease (Fig. 1) and the entomopathogenic fungus Entomophaga maimaiga (Humber, Shimazu et Soper) (Fig. 2). In the summer 2013, gipsy moth deposited a small number of egg masses (the decline phase) which is the result of both extensive control measures from the air during 2011 and 2012, and thanks to natural population decline at the locations where there was no suppression.

Early season oak defoliators Population levels of early season defoliators from the families Geometridae, Tortricidae, Noctuidae and Tenthredinidae were monitored using the accepted methods: a) sticky traps, b) taking branches during the winter period and their growing in laboratory conditions, c) on spring branches in the forest, immediately after leafing, d) assessment of defoliation in the stands at the time when caterpillars stop nutrition. During the past period, early season defoliators were suppressed on significant areas, by treating oak forests and poplar plantations both from the air (6560.8 ha) and from the ground (489.8 ha). In 2004, early season defoliators occurred in higher density in Gornje Podu- navlje (loc. Kozara and Štrbac; 44.0 ha), on the territory of National Park Fruška Gora (cca 150 ha), and in clonal poplar plantations at Mužljanski Rit (cca 300 ha) but no suppression actions were undertaken (Table 2). Early season defoliators were recorded also in 2005, and they were suppressed from the ground on small areas. Caterpillars of green oak tortrix moths (Tortrix viridana L.) and geometrid moths were controlled by fogging at the site Gornje Podunavlje (preparation Decis 2.5- EC; 63.1 ha). At Mužljanski Rit noctuid moths (fam. Noctuidae) were controlled in juvenile clonal poplar plantations using the preparation Fenitrothion 50-EC on 129.3 ha (Table 2). During 2004 and 2005, there was a severe defoliation in poplar plantations at Mužljanski Rit. In some parts of the area, the defoliation was caused by caterpillars from the families Noctuidae (Orthosia incerta, Orthosia gotica, Orthosia populi) and Geometridae (Erranis defoliaria). For that reason, in the spring 2006, it was de-

72 cided to air spray the plantations on the area of 497.5 ha (Table 2). The suppression with the preparation Decis 2.5-EC was successful. Population levels of early season defoliators reached the critical threshold during 2007 in numerous oak stands of Forest Estate Sremska Mitrovica, so in the spring 2008, an air spraying action was organised on 1039.4 ha. The treatment of the stands at Raškovica-Smogvica, Smogva-Grabova Greda and Vinična with the preparation Foray 48B showed a very good result (Table 2). Unfortunately, the complexes in which early season defoliators were not controlled suffered severe defoliations in the spring 2008, and in a part of Estate area, the defoliation was complete (loc. Blata-Malovanci, Dobreč, Visoka Šuma-Lošinci; 2088.0 ha). Poplar plantations at the location Mužljanski Rit were left without protection and the caterpillars of geometrid moths and noctuid moths defoliated more than 70% of the foliage. Geometrid moths were suppressed from the ground during the spring 2008 in one-year-old and two-year-old clonal poplar plantations in Posavina (199.5 ha) and Mužljanski Rit (97.9 ha) with good results (Table 2). As the outbreak of geometrid moths was not stopped, additional suppression actions were undertaken on significantly larger areas in the following year. In the spring 2009, oak stands in Posavina (Forest Estate Sremska Mitrovica, Etiol ULV, 3000.0 ha) and at Vršački Breg (Foray 48B; 1000.0 ha) were treated from the air. The multiannual outbreak of early season defoliators at Mužljanski Rit was stopped by the protection of poplar plantations (Etiol ULV; 480.5 ha) (Table 2). Early season defoliators in FE Sremska Mitrovica were suppressed outside the optimal period, i.e. with a delay of 7-8 days (April 29th, 2009), when the caterpillars molted into higher instars and thus became more resistant to insecticides (Etiol ULV at a rate of 0.8 L/ha). Despite the treatments, oak stands at Blata-Malovanci and Visoka Šuma-Lošinci suffered a heavy to severe defoliation. The forest Dobreč was completely defoliated (159.0 ha) because the application of chemical control was not allowed (vicinity of sources of drinking water for the town Ruma). It should be noted that the results of the experimental treatment of oak stands at Žeravinac (compartment 30) with the preparation Avaunt 15-SC were poor. In addition to being too late, caterpillars were controlled at lower rates, compared to the rate applied in the treatment of poplar plantations at Mužljanski Rit (Etiol ULV at a rate of 1 L/ ha; April 18th 2009). Thanks to aerial spraying over extensive areas (4530.5 ha), and partly thanks to natural population decline, the areas infested by these insects were significantly reduced. An additional aerial suppression of early season defoliators was organised at Vršački Breg in the spring 2010 using the preparation Foray 48B on 493.4 ha (Table 2), and the action was assessed as very successful. Significant damage caused by green oak tortrix moth (T. viridana) and geometrid moth caterpillars were recorded in 2010 only in the area of Gornje Podunavlje (loc. Štrbac and Slatina). The infestation was recorded on 183.8 ha. During 2011 and 2012, the population level of early season defoliators was low, i.e. far below the critical numbers (Table 2).

73 In the spring 2013, there were visible defoliations in the crowns of poplar trees at Mužljanski Rit, which announced the initiation of a new outbreak. At that location, poplar plantations were established on the soils of heavy mechanical composi- tion, which are unsuitable for poplar cultivation (Živanov, Jovin, 1983). Frequent outbreaks of noctuid moths and geometrid moths indicate that poplars are not in their physiological optimum at this site. In the spring 2013, common maple trees in the undergrowth of oak stands at the sites Štrbac and Kozara (Gornje Podunavlje) were completely defoliated by geometrid moth and noctuid moth caterpillars, while pedunculate oak and Turkey oak trees were not infested. Mass infestations by caterpillars of early season defoliators in previous years (2004, 2005, 2010) were the consequence of a less favourable site for the growing of hard broadleaves. These were the cases of Turkey oak and pedunculate oak stands established mostly on degraded types of chernozem (CH) and on solonetz (SN) (Kadović, 1983; Galić, 2003). It should be noted that this is our first statement on the incidence of local insect outbreaks at the sites which are less favourable for the establishment and cultivation of hard and soft broadleaves in Vojvodina.

Chrysomelidae – leaf beetles Leaf beetles (Chrysomela populi and Phyllodecta vitellinae) accounted for a dominant percentage in the defoliation of juvenile plants in poplar nurseries and plantations. They were suppressed chemically each year using different preparations (Actara, Calypso, Fenitrothion, Labaycid, Etiol liquid, Confidor, Decis, Talstar, Per- fekthion, Fastac, and Ciprazor). The protection was timely and efficacious, therefore significant defoliations were prevented, and the plants were given unrestricted development. In juvenile plantations of clonal poplars in Posavina, there were unique outbreaks of willow leaf beetles – Ch. vigintipunctata and P. versicolora. In the spring 2008, the infestation of Ch. vigintipunctata reached the level of a local outbreak. The density of this species was never high in Vojvodina, i.e. its presence in poplar and willow nurseries and juvenile plantations was individual. The adults of this pest were first detected in mid-May at Kupinski Kut in 1-year to 2-year-old poplar plantations, and somewhat later also at Grabovačko-Vitojevačko Ostrvo. The pest was suppressed with full success using the preparations Decis and Etiol liquid on 54.9 ha. It is known that C. vigintipunctata is trophically more related to willow. The fact that it occurred in juvenile poplar plantations in the vicinity of older willow stands, indicates that willow as the principal host in the diet of this leaf beetle, was perhaps of the decisive significance in its outbreak on poplar. From the nineties of the last century, the pest has more massively occurred also in the area of Central Europe (Czech Republic, Slovakia). The authors from these countries (Urban, 1997, 2005; Kodrik et al., 2006) report that frequent outbreaks of C. vigintipunctata in

74 Table 2 Areas infested by early season defoliators in Vojvodina and areas treated from the air and from the ground during the period 2004-2013

Total Suppression of early season defoliators (ha) Year infested and applied preparations area (ha) from the air from the ground 2004 494.0 - - total 192.4 ha Decis 2.5-EC (active substance deltamethrin) 2005 814.5 - (FE Sombor, 63.1 ha) Fenitrothion 50-EC (a.s. fenitrothion, conc. 0.15%) (FE ‘Banat’ - Pančevo, 129.3 ha) 497.5 ha Decis 2.5-EC (a.s. deltamethrin) 2006 797.5 - (0.2 L/ha + 2.8 L naphtha D1/ha) (FE ‘Banat’ - Pančevo, 497.5ha) 2007 539.7 - - total 297.4 ha 1039.4 ha Ciprazor 20-EC (a.s. cyper- Foray 48B methrin, conc. 0.03%) 2008 3626.9 (Bt subsp. kurstaki) (FE Sremska Mitrovica, 199.5 ha) (3 L/ha) Etiol liquid (a.s. malathion, conc. (FE Sremska Mitrovica, 1039.4 ha) 0.30%) (FE ‘Banat’ - Pančevo, 97.9 ha) total 4530.5 ha Etiol-ULV (a.s. malathion) (1 L/ha + 2 L naphtha/ha) (FE ‘Banat’ - Pančevo, 480.5 ha) Etiol-ULV (0.8 L/ha + 2.2 L naphtha/ha) 2009 4689.5 (FE Sremska Mitrovica, 3000.0 ha) - Foray 48B (3 L/ha) (Bt subsp. kurstaki) (FE ‘Banat’ - Pančevo, 1000 ha) Avaunt 15-SC (a.s. indoxacarb) (FE Sremska Mitrovica, experimental, 50.0 ha) 493.4 ha Foray 48B (3l/ha) 2010 677.2 - (Bt subsp. kurstaki) (FE ‘Banat’ - Pančevo, 493.4 ha) 2011 0 - - 2012 0 - - 2013 200.0 - -

75 willow plantations were accelerated by extremely dry and hot weather at the end of the last century and at the beginning of this century, and by primary physiological weakening of willows caused by climate changes. In the spring 2010, there was a high density of blue-coloured poplar leaf beetle – P. versicolora. The pest was recorded and chemically suppressed at Grabovačko- Vitojevačko Ostrvo. The plantations of the clone Populus deltoides (182/81) were treated with the preparation Etiol liquid on 11.2 ha.

Small weevils from the genera Byctiscus, Phyllobius and Chlorophanus Occasionally, high densities of small weevils from the genera Byctiscus, Phyl- lobius and Chlorophanus were recorded on poplars. Their outbreaks occurred in juvenile poplar plantations in Podunavlje (loc. Kamarište, Plavanjske Šume) during 2004, 2005, 2009 and 2010.

Xylophagous insects on poplars In poplar nurseries and juvenile plantations in Vojvodina, there were frequent and sometimes very numerous injuries caused by xylophagous insects (Paranthrene tabaniformis L. and Cryptorrhynchus lapathi L.). Dusky clearwing was suppressed by injecting petrol into larval galleries during the period August-September, and poplar and willow borer was suppressed by treating the tree bark in early spring with the insecticides Lebaycid and Etiol liquid at higher concentrations.

Pygaera anastomosis L. It was recorded in June 2011 in juvenile poplar plantations in Posavina (loc. Banov Brod, Stara Rača, Martinački Poloj), in the proportion of a local outbreak. The pest endangered 1-9-year-old plantations of the clone I-214, and it occurred individ- ually in P. deltoides plantations on the area of 361.4 ha. In a part of the infested area, in 1-year-old and 2-year-old poplar plantations, caterpillars were suppressed with the preparation Talstar (114.1 ha). In older plantations (7-9 years) in which there was no protection, caterpillars caused defoliations of different intensities (10-50%), and in a part of the area they caused defoliation (cca 6-7 ha) (Fig. 3). The outbreak decline was caused by a high infection of caterpillars of the second generation with a virus disease and by the presence of beneficial insects Calosoma( sycophanta).

Nycteola asiatica Kr. - the eastern nycteoline This noctuid moth species was identified on poplar clones of the speciesPop - ulus x euramericana in several nurseries and juvenile plantations during 2005, 2006, 2012 and 2013. Its caterpillars fed on the seedling tops with different intensities.

Proleucoptera sinuella Rtti. – poplar leaf miner It outbreaks occasionally in poplar nurseries and juvenile plantations. Its attacks were recorded in juvenile poplar plantations at Potisje (vicinity of Kanjiža),

76 Fig. 3. Defoliation in poplar plantation (cl. I-214) by Pygaera anastomosis killed by virus disease loc. Banov Brod, June 2011) Posavina (loc. Banov Brod), and on the Institute’s experimental field (Kaćka Šuma). Suppression actions were not undertaken.

Aphididae - aphids They were identified on almost all major forest species grown in Vojvodina (oak, narrow-leaved ash, poplar, willow, black locust, pine). Their colonies were the most abundant in clonal poplar nurseries and juvenile plantations. The most frequently identified species on poplars were Chaitophorus leucomelas Koch and Pterocomma populeum Kalt. Aphids were controlled with insecticides in juvenile poplar plantations of Podunavlje and Posavina during 2006, 2007, 2010 and 2013.

Stereonychus fraxini Deg. – ash weevil Narrow-leaved ash stands in Vojvodina were infested by ash weevil – Stereo- nychus fraxini. The pest was recorded in 2008 over large areas in Posavina (Forest Estate Sremska Mitrovica), where ash stands were under severe and very severe infestations on 684.6 ha (more than 50% of leaves), and medium infestation (10-30% of leaves) on 3135.3 ha. In the following year, the areas infested by ash weevil were multiply reduced thanks to the natural decline of its population caused by biotic and abiotic factors. In Gornje Podunavlje (Forest Administration Apatin), ash weevil occurred occasionally in high density, and significant damage of the foliage and even the defoliation were recorded in some stands in 2005, 2007, 2009 and 2010. However, suppression actions were neither planned nor undertaken anywhere in Vojvodina in the past period.

Neodiprion sertifer Geoffr. – European pine sawfly It caused occasional infestations and outbreaks in Scots pine plantations at Deliblatska Peščara and Subotička Peščara. This was the case in 2005 and 2006 when significant damage (10-40% of needles) was recorded. The pest was suppressed dur-

77 ing May 2006 in Scots pine plantations at Subotička Peščara using Fenitrothion on 9.7 ha.

Acantholyda hieroglyphica Christ. – spinning pine sawfly It was encountered during 2011 and 2012 in the new established Austrian pine plantations at Subotička Peščara. The pest was suppressed mechanically – by remov- ing and crushing the larval nests on the area of 12.4 ha (Fig. 4).

Fig. 4. Nest of A. hieroglyphica larva on Austrian pine seedling (Subotička Peščara, June 2011)

The species Helicoverpa armigera Hüb, Metcalfa pruinosa Say and Anomala sp. were identified for first time in forest ecosystems of Vojvodina. The caterpillars of cotton bollworm (Helicoverpa armigera) were detected on poplar seedlings in the nursery Ljutovo on the river Tisza in July and August 2007. Feeding on the tips of terminal sprout caused injuries in the form of holes (Fig. 5). The plant inspection in the nursery showed that terminal shoots were damaged ex- clusively on the clones I-214 and Pannonia which belong to the species Populus x euramericana. Caterpillars were successfully suppressed using preparation Decis 2.5-EC (Pap et al., 2008). Later on, in this nursery, cotton bollworm was recorded two times (2008, 2011). They were individual attacks – suppression measures were not undertaken. On the Experimental field of Institute of Lowland Forestry and Environment, cotton bollworm was identified in August 2008. Individual caterpillars were found on the tops of poplar shoots originating from european black poplar (P. x euramericana cl. Pannonia and P. nigra x P. maximowiczii cl. 9111/93). Planthopper Metcalfa pruinosa was identified for first time in Vojvodina in 2009 in a private nursery of ornamental trees and shrubs in Srem. The nursery is located near Belgrade-Zagreb highway and the border crossing with Croatia. Its larvae and adults were identified on nursery stock from the genera Prunus, Pyrus, Junipe- rus, Thuja, and Chamaecyparis, and also on the spontaneous vegetation in the vicin-

78 Fig. 5. Poplar terminal shoot damaged by cotton bollworm caterpillars (Nursery Ljutovo, July 2007) ity of the nursery (white poplar, weed plants). In 2011, the species was identified in various densities also on forest tree species (poplar, pedunculate oak, narrow-leaved ash, black locust). Our first records indicate that M. pruinosa does not cause visible symptoms of chlorosis, leaf discolouration or the deformations characteristic of the activities of sucking insects, so for the time being there is no need for its chemical control. In the middle of June 2012, numerous adults of one of Anomala species inten- sively feeding on the foliage were detected in juvenile poplar plantations in Posavina (loc. Banov Brod) (Fig. 6). As the defoliation of juvenile poplars progressed rapidly, it was decided to undertake the suppression measures. After unsuccessful treatments of plantations with the preparation Talstar 10-EC (June 16th, 2012), suppression was repeated using the insecticide Lebaycid EC-50, with full success. At the same site, Anomala sp. also occurred in the following year at the degree and intensity which required its suppression.

Fig. 6. Anomala sp. adult beetles on poplar leaves (June 2012)

79 CONCLUSION

In broadleaf forests and plantations in Vojvodina during the past period, there was a great number of insect pests. Gipsy moth (Lymantria dispar) and the insects in the group of early season defoliators of oak, poplar and willow were designated as the most significant ones from the aspect of detrimental effects. In juvenile poplar plantations significant damage was caused by xylophagous insects (Paranthrene tabaniformis and Cryptorrhynchus lapathi), and in narrow-leaved ash stands, defoliations were caused by ash weevil (Stereonychus fraxini). Other insect pests were recorded occasionally and on smaller areas. Multiannual monitoring of insect pests on the territory of Vojvodina showed that the occurrences of local outbreaks were more frequent and of higher intensities at the sites which were less favourable for the cultivation of the particular tree species.

Acknowledgements: This paper was realized as a part of the project ‘Studying climate change and its influence on the environment: impacts, adaptation and mitigation’ (43007) financed by the Min- istry of Education and Science of the Republic of Serbia within the framework of integrated and inter- disciplinary research for the period 2011-2014.

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